Cryptology ePrint Archive: Report 2009/064

On the Data Complexity of Statistical Attacks Against Block Ciphers (full version)

Céline Blondeau and Benoît Gérard

Abstract: Many attacks on iterated block ciphers rely on statistical considerations using plaintext/ciphertext pairs to distinguish some part of the cipher from a random permutation. We provide here a simple formula for estimating the amount of plaintext/ciphertext pairs which is needed for such distinguishers and which applies to a lot of different scenarios (linear cryptanalysis, differential-linear cryptanalysis, differential/truncated differential/impossible differential cryptanalysis). The asymptotic data complexities of all these attacks are then derived. Moreover, we give an efficient algorithm for computing the data complexity accurately.